In the field of organic chemistry, reaction products different in form from their starting materials can be obtained by means of a large number of reaction sequences. Organic starting materials particularly amenable to reaction are alkene compounds, otherwise known as olefins. Olefins are characterized by the presence of one or more carbon-carbon double bonds. Reactions involving olefins usually occur at the carbon-carbon double bonds. The double bond can be eliminated by addition of atoms to the olefin molecule. The double bond can also be shifted from one carbon-carbon couple to another within the molecule. The double bond can also be cleaved to form two or more smaller molecules from one olefin molecule having one or more double bonds. Cleavage is accomplished by a small number of reaction sequences such as ozonolysis, oxidation and the like. Generally, cleavage occurs by the addition of oxygen to the double bond carbons which then destroys the bond between the carbons.
The presence of a substituent group on the olefin compound sometimes permits the double bond to be broken under less vigorous conditions. One such substituent is the carbonyl group, which consists of a carbon doubly bonded to oxygen. A carbonyl group having its double bond conjugated with the olefin double bond can activate the olefin double bond and cause it to break in the presence of alkaline catalyst, heat and water. This reaction is known as a reverse or retro-aldol condensation which is subject to side reactions and reaction product condensations. In the presence of only heat and water, typically no reaction occurs.
One reference has been found which describes the cleavage of a substituted conjugated cyclohexanone molecule in the presence of heat, pressure and water without any added alkaline catalyst. The reaction as cited in Annalen, Vol. 289, p. 337 (1896), involved the formation of acetone and 3-methyl-cyclohexanone in an autoclave at 250.degree. C. from pulegone and water. It is believed that pulegone underwent reaction under the above conditions because the position of the substituents on the cyclohexyl ring caused a destabilization of the olefin, permitting reaction to occur.
German Patent No. 875512 to Binapfl discloses a procedure for splitting certain unsaturated ketones having the carbonyl double bond conjugated with the carbon-carbon double bond. Splitting occurred when the ketone was heated in the presence of water, preferably with added acid. The hydrogen atom in the water molecule was directed to the carbon atom of the double bond closest to the carbonyl group, with oxygen being directed to the remaining carbon of the double bond, thereby forming a product ketone or aldehyde. For example, a mixture of cyclohexylidenecyclohexanone-2 and water was heated to a temperature of about 295.degree. C. to 300.degree. C. in a pressure vessel to yield cyclohexanone.